Masterstat



March 3, 1931.

P. F. SHIVERS 1,795,149.

MASTERSTAT Filed May 4 1928 2 Sheets-Sheet 1 BLUE RED r: l l 102 u u Q E r10 3 2 CUNTROL MUTOR Zlwwzwtoz MOTOR Paul FJhzVem,

March 3, 1931. P. F. SHIV'ERS MASTERSTAT Filed May 4 1928 amnion Paul 1 JhZI/e'rJ,

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61cm wag 5 15 The lnstrument formin Patented Mn. 3, 1931 UNITED STATES PATENT oFnce PAUL F. SHIVEBS, OF WABASH, INDIANA, ABSIGNOB 'IO nmxmoms-noxmr.

REGULATOR COMPANY, OF MINNEAPOLIS, MINNESOTA, A CORPORATION 01' DELA- WARE MASTEBSTA'I.

Application filed Icy 4, 1928. Serial l'l'o. 275,248.

The primary object of my invention is to provide a single instrument unit for controlling the circuits of the fuel motor and circuit controlling motor of a fuel burning unit con- 5 trol mechanism, to be affected by the condition of the boiler or heating unit, as distinguished from the burner unit, of such character as to be adjustable to predetermined upper and lower operating limits, and also 19 so formed that, in case of the establishment of abnormally high temperature conditions or a failure of the heat affected element, the fuel motor circuit will be broken at an emergency point.

the sub eot matter of this application 1s now commonly known in the trade as the Honeywell masterstat andis intended to be used in conjunction with a room thermostat,'and a combustion control.

The accompanying drawings illustrate my invention:

Fig. 1' is an elevation in partial vertical section of a heater with my improved masterstat in elevation and slightly exaggerated as to the relative size.

Fig. 2, a rear elevation of my improved instrument with the rear cover removed and a portion broken away.

Fig. 3, a front elevation of the instrument with a portion of the front cover and a portion of the lower casing broken away.

Fig. 4, a perspective view, in partial-section, of the yielding driving connection for the indicator finger and movable contacts.

Fig. 5, a perspective of the indicator finger and associated contact fingers.

Fig. 6., a section on line 6, 6 of Fig. 2.

Fig. 7, a fragmentary perspective view of the emergency latch and the associated operating finger.

Fig. 8, a diagram of a control installatlon including my present improved instrument.

In the drawings 10 indicates a cup-like bellows 11, commonly called a sylphon to the interior of which is connected a flexible tube-12 provided at its end with a bulb 13, the bulb, tube and bellows being filled with an expansible liquid or gas, in the well known casing within which is mounted a metallic manner to an extent sufiicient to cause some elongation of the bellows at normal atmospheric temperatures.

Covering the'open upper end of cup 10 is a casing 15 which contains and protects the mechanism now to be described. Resting upon the upper end of the bellows 11 is the head 16 of a vertical stem 17 which is slidable through the bearings 18 and through a bushing 19 which is threaded in a bracket 20 conveniently formed integral with casing 15. Secured to stem 17 is a collar 21 which forms an abutment for two compression sprin s 22 and 23'which lie' between collar 21 an the lower end of bushing 19. Bushing 19 is ver tically adjustable in bracket 20 and is held in any desirable position of adjustment by screw 25. Spring 22 is preferably lighter and longer than spring 23 so that, at ordinary atmospheric tem eratures spring 23 does not contact with bushing 19.

Secured to the upper end of stem 17 is a collar provided with a radial arm 31 which, at its outer end, is turned upwardly substantially parallel with the axis of stem 17 and its tip 32 turned back toward the stem, for a purpose which will appear. Pivoted at 33, on a horizontal axis, is a latch 34 one arm of which is formed, at 35, to coact with an emergency switch S and its other arm formed, as indicated at 36, to have a one way coaction with finger 32.

The switch S comprises a pair of fixedterminals and 41'intended to be connected in series with the fuel motor, or other motor, to be controlled. A spring plate 42'with spring fingers 43 and 44 is biased away from terminals 40-41 but, when urged against its bias, fingers 43 and 44 will bridge terminals 40 and 41. Secured to the plate 42 is a strip of insulating material 45 the u per end of which is adapted to be engaged y the catch portion 35 of the latch 34-and held by it in such position as to hold the spring fingers 43 and 44 of plate 42 in bridging contact with the fixed terminals 40 and 41.

Threaded through latch 34, in alignment which is accessible through an opening 51 in 88, is a metallic contact finger 90 and secured casing 15, said opening being normally closed to disc 89 on the face most remotefrom disc by the screw 52. I 88 1s a similar contact fin er 91 and these two The bridging element 42-43-44 may be fingers are bound toget er upon an interrestored to its operative position, as shown diate insulation 92, as shown in Fig. 5 the in Fig. 2, against the bias of the spring plate arrangement b e1ng such that the are me- 42, by means ofa finger 56 (-Fi 2)'carr1ed chamcallyaumt but electrically 1n ependent. at the lower end of a stem 5 journalled Connected to finger 90 1s a metal volute 93 through the upper wall of casing 15 and roand connected to finger91 1s a m etal volu te vided at its outer end with a knurled hea 58 94. These two volutes are shown in Fig. 5 in by means of which the fin or 56 may be heavy dotted 'lll'lBS merely for olearness of swung into engagement wit plate Y45 and illustration. They are continuous metal the structure 42--434445 urged to the members provided for the purpose of forming position shown in Fig. 2. a flexible electrical connection between 'the Secured to stem 17 is a ring 60 (Figs. '2 contact fingers 90 and 91 and the fixed terand 4) which carries a rack 61 arranged parminals 95 and 96 respectively (Fig. 3). ourallel with the axis of stem 17. Rack 61 naled on shaft 63 behind the indlcatorfinger meshes with a pinion 62 journalled, on a unit are two contact carrying indicator arms shaft 63 which is journalled in a supple- 101 and 102. Arm101carr1esalowtemperamental frame 64 which, in turn, is secured ture contact 103, which is nsulated from its within casing 15. Secured to pinion 62 is a arm and connected by a suitable flexible conradial arm '65 provided at its end with an nection with one of the fixed binding posts of axially extending finger 66. I the instrument. Similarly arm 102 carries Secured to shaft 63 is a radial arm 67 simlan insulated high temperature contact point lar to arm 65 and, at its end, provided with 104 which is also connected by a suitable flexan axially extending finger 68 like finger 66. ible connector to one of the fixed binding The two fingers 66 and 68 are projected toposts of the instrument. The two contact ward each other with their free ends closely points 103 and 104 are so radially spaced from adjacent. J ournalled upon the shaft 63 beshaft 63 as to be contactible by the fingers 91 tween the two arms 65 and 67 are two similar and 90 respectively.

. arms 70 and 71 each having its outer end bent One of the uses to which my improved inso as to form fingers 72 and 73 respectively strument may be put is indicated in the dialying parallel with shaft 63 and upon opposite gram Fig. 8 wherein R isan ordinary room sides of the fingers 66 and 68. The two hnthermostat, FM is the fuel motor of an 011 gers 72 and 73 are urged toward each other burning device in which the oil is delivered and yieldingly held against the fin ers 66 an to the nozzle by the action of the fuel motor, 68 by means of a spring 75 the en 5 of whlch M is my improved masterstat which forms are anchored respectively upon the arms the principal subject matter of this applicaand 71, the above described construction and tion and CM is a switch control motor by arrangement is such that rotation of pinion means of which the move ents of the fuel 62 in either direction will cause equal rotamotor are determined accgffiiing to the coortion of shaft 63 so long as movement of the dinated. demands of the room thermostat and shaft is unobstructed. The movement'of the the masterstat the arrangement being such shaft being accomplished by ap lication of that a call for heat by the room thermostat pressure by finger 66 against the gers 72 or will result in an energization of the fuel only 73 and the transmission of that pressure when contact finger 91 is in contact with terthrou h spring to the companion fingers minal 103; and that whenever contact finger 73 or 72 and the transmission of the force by 90 contacts with terminal 104 the control that finger to the finger 68 of arm 67 and motor will be energized to cause a deenergithence to the shaft 63. Whenever an obstruc- 'zation of the fuel motor. tion to movement of shaft 63 is encountered The operation is as follows: arm 65 may continue its movement by displac- Tube 13 is preferably laid upon the crown ing one or the other of the arms 70,71, depen sheet of the boiler, as indicated in Fig, 1 and ing upon the direction of movement of pin10n arm 101 is set at a point indicating the lowest temperature which is desired in the boiler Rack 61 is held in-mesh with gear 62 by under working conditions, while arm 102'is means of a spring finger 80. set to indicate the highest temperature which Secured to shaft 63, most conveniently by is desired in the boiler. Screw 50 is then so frictional engagement, is the indicator and adjusted that whenever the temperature of contact finger unit shown in Fig. 5. This the crown sheet reaches a point a degree or unit comprises a central core or hub to two higher than the highest temperature which the indicator finger 86 is secured. which is to be desired in the boiler, at any set- Secured to hub 85 are three discs 87, 88 and ting of arm 102, the upper end of stem 17 will 89 of insulating material. come into contact with latch 34 and lift it Secured to'disc 87, on the face adjacent disc from the upper end of plate 45 so as to permit the bridging piece of switch S to move away from engagement with terminals 40 and 41 and thus break the circuit of the fuelmotor. So long as the boiler temperatures lie below the desired temperature indicator 86 will lie somewhere between the two arms 102 and 101, with fin r 90 out of contact with terminal 104 whic will lie over to the left (Fig. 3) with fin er 91 in contact with terminal 103.

If now t ere is a'call-for heat b the room thermostat the control motor wiil'be energized and a circuit established for the fuel motor and when the room thermostat ceases its demand for heat there will be another energization of the control motor to cause a deenergization of the fuel motor. If, however, the fuel motor remains energized long.

enough to cause the boiler temperatures to rise to the specified maximum before the room thermostat is satisfied finger 90 will be brought into contact with terminal 104, and the control motor will be energized to cause a deenergization of the fuel motor.

The movement of the contact fingers 90 and 91 is produced by the expansion and contraction of the bellows member 11, dueto the heat within the boiler and in the normal range of operation neither the upper end of stem 17 nor the finger 32 will contact with latch 34 sufiiciently to release plate 45. If, however, the consumption of fuel continues to a o1nt where the crown sheet is over heated either to a point of desired maximum water temperature or due to absence of water in the boiler, depending upon the adjustment-- of'screw 50, the upper end of stem 17 will engage with the head of screw 50 and move latch 34 to releasing position whereupon the circuit to the fuel motor will be automatically broken at switch S and the fuel motor can only be restored by manual restoration of switch S. On the other hand, if, for any reason, a leak should be caused in the system 11-12-13, the bellows 11 would become deflated to such an extent as to permit finger 32, under the action of spring 22, to descend into engagement withlatch 34 and retract said latch from the plate 45 and thus cause a break in the fuel motor circuit at switch S. When the switch S has been released as a result of deflation of bellows 11 it will not be possible to restore the switch S to normal position without first repairing the trouble in the bellows system because, when plate 45 is swung to the position shown in Fig. 2 by a manipulation of finger 56 it will not be caught by latch 34 because said latch will continue to be held down by finger 32.

It will be readily understood that the stem 17 may be moved by means other than the particular means shown and described without departing from my invention the broad feature of which resides in the combination of a switch biased in one direction, retained against its bias by a latch, and the latch withdrawn by abnormal movement of the 17 in either direction.

I claim as my invention: 1.-The combination of comprising a movable member biased in one direction, a latch coo crating with said movan electric switch able member to ho d the same against its bias, and a reciprocable actuator having-two oppositely set one-way connections with said latch whereby movement of the reci rocable element in either direction beyon a pre determined limit will act to withdraw the latch.

2. In a circuit controlling instrument the combination of an arm having an intermediate pivot, and an electric switch so associated with said arm as to be in circuit closing position in one position of the arm tively upon opposite sides of its pivot whereby movement of the actuator in either direction beyond a predetermined stroke will shift saidarm to determine the condition of the switch. I

3. A circuit controlling instrument comprising an electric switch having a movable element biased open, a latch for retaini said movable element in circuit closing position against its bias, a thermostatic bellows,

.a reci-procable stem engaging said bellows, a

a reciprocable stem engaging said bellows said stem having two oppositely set one-way contacts with the latch each acting to retract the latch.

5. A circuit controllinginstrument' comprising a temperature aflected element, a reciprocable element associated with said temperature affected element, a contact element operated by said reciprocable element through the medium of a connection yieldable in each direction relative to the contact element' whereby the movement of the contact element may be obstructed without objectionable effect thereon or upon the actuator therefor, two contact elements arranged at opposite sides of the first mentioned contact element, and independently adjustable supports for said last -mentioned contact elements.

6. A circuit controlling instrument comprising a temperature affected element, a reciprocable element associated with said temperature affected element, a contact element erated by said reciprocable element t irough the medium of a connection yieldable in each direction relative to the contact element whereby the movement of the contact. element may be obstructed without objectionable effect thereon or upon the actuator therefor, two contact elements arranged at opposite sides of the first mentionedcontact element, independently ad-- justable supports for said. last mentioned contact elements, a switch having a movable element biased in one direction, a latch for holding said movable element against its bias 1:; and two one-way engagements between the reciprocable element and said latch said'two engagements being relatively spaced an amount suiiicient to move the first mentioned contact element from one of .its associated contact elements to the other without afi'ecting the latch.

7. A circuit controlling instrument comprising a temperature affected element, a reciprocable element associated with said tem- 26 perature afi'ected element, a contact eIement operated by said reciprocable element and ment displaced against its bias, and an actutwo contact elements arranged at opposite sides of the first mentioned contact element independently adjustable supports for said 30 last mentioned contact elements, a switch having a movable element biased in one direction, ,a latch for holdin said movable ele-' ment against its bias an two one-way engagements between the reciprocable element and said latch said two enga ementsgbeing relatively spaced an amount so cient to'move the first mentioned contact element from one of its associated contact elements to the other without affecting the latch. 8. A circuit controlling instrument comprising a group of coordinated contacting elements some of which are relatively adjustable toward and from others and some ofwhich are movable toward and from others by b abnormal movement of the actuator in either direction beyond a predetermined range. I

9. A control instrument comprising a shiftable controller element yieldingly biased'in one direction, a latch arranged to normally retain said controller in displaced position against its bias, and an actuator for said latch having two spaced ortions arranged relative to said latch to shi said latch to release position by movement of the actuator in oppo- I site directions.

10. A control instrument comprising a shiftabie controller element yieldin 1y biased in one direction, a medially pivote latch ar- 1 ranged to normally hold the controller elepre etermined positions at oppo- I 

